A mobile terminal has recently been released in a multi-mode form having two or more wired/wireless access interfaces. With the development of wireless networking technology, wired/wireless networks having various characteristics are mixed and distributed all over the words. In this environment, a user's desire to access an optimal network is increasing in order to be supplied with the best service quality at his current position without being restricted to a specific network. A user prefers a high bandwidth and cheap communication service if possible. The users of mobile terminals want to be supplied with seamless service without being restricted to mobility while having access to heterogeneous networks.
In order to realize such communication service, there is need for technology guaranteeing common IP-based mobility which is capable of integrating, managing, and operating various kinds of access networks.
IEEE 802.21 Working Group was formed on March, 2004 in order to support seamless handover between heterogeneous networks, and relevant technology was named Media Independent Handover (MIH). In MIH technology, a multi-mode terminal having a network access interface with two or more different characteristics was taken into consideration. Furthermore, the scope of work is both handover between IEEE 802-series networks and handover between non-IEEE 802-series networks, such as handover between networks having different characteristics within IEEE 802-series networks, such as WiBro and WLAN, and handover between WiBro and a 3GPP network.
Seamless mobility service provided through IEEE 802.21 MIH technology means that quality of service is guaranteed to the extent that, when a user terminal performs handover between different heterogeneous networks, the user does not feel the degradation of quality of service by having the user satisfied with the quality of service provided in a previous network to the highest degree.
Handover between heterogeneous networks having different typical characteristics generates handover between different IP subnets. Accordingly, in this handover, a mobility management protocol for continuously maintaining IP connection in a previous network needs to be performed. A delay problem according to IP setting, subnet mobile detection, and mobility registration processing in a new network has been pointed out in IP mobility management protocols, such as Mobile IP and Proxy Mobile IP. This problem required close association with an underlying layer.
IEEE 802.21 MIH technology stipulates a structure, service, and a protocol procedure in which a mobility management protocol optimizes the performance of user application service upon handover between heterogeneous networks through close association with underlying physical and link layers.
Accordingly, researches are being carried out on technology for supporting the mobility of wireless communication terminals through MIP (Mobile IP), major mobility support technologies extended from MIP, and information exchange and mutual actions between heterogeneous networks.